Safety vs Efficiency in the Development of a High-Energy Compound

A scalable route to 5-(2-carboxy-pyridin-2-yloxy)-benz[1,2,5]oxadiazole (3) is demonstrated. The synthesis was designed to minimize potential safety issues with a previously practiced route and, in particular, to avoid the handling of 5-hydroxybenzofurazan, which was found to decompose with a large energy release at relatively low temperatures. The new route builds the benzofurazan moiety onto a nicotinonitrile core to avoid high-energy intermediates with low onset temperatures of decomposition.